The present invention relates to chiral phosphinitemothyl-oxazolines; to a process for the preparation thereof; to intermediates used in the preparation thereof; to metal complexes with metals selected from sub-groups I and VII of the Periodic Table of the Elements (d-10 and d-8 metals, referred to as TM8 metals hereinbelow) and phosphinitomethyl-oxazolines as ligands; to a process for asymmetric synthesis by means of an addition reaction between hydrogen, borohydrides or silanes and a carbon-carbon or carbon-hetero atom multiple bond in prochiral organic compounds or by means of an addition reaction between C-nucleophiles or amines and allylic compounds, especially for asymmetric hydrogenation of carbon-carbon or carbon-hetero atom multiple bonds with hydrogen, in the presence of catalytic amounts of the metal complexes; and to the use of the metal complexes as catalysts for asymmetric synthesis by means of an addition reaction between hydrogen, borohydrides or silanes and a carbon-carbon or carbon-hetero atom multiple bond in prochiral organic compounds or by means of an addition reaction between C-nucleophiles or amines and allylic compounds, especially for asymmetric hydrogenation of carbon-carbon or carbon-hetero atom multiple bonds with hydrogen.
G. Helmchen and A. Pfaltz in Accounts of Chemical Research, Volume 33, Number 6, pages 336 to 345 (2000) describe chiral phosphinophenyl-oxazolines as P,N ligands for asymmetric catalysts that are used inter alia in the enantioselective addition of nucleophiles to carbon-carbon double bonds. The oxazoline ring is substituted with bulky groups in the xcex1-position to the nitrogen atom to form an asymmetric centre (carbon atom).
It has been found, surprisingly, that it is possible to prepare in simple manner P,N ligands that contain a phosphinitemethyl group in the xcex1-position to the nitrogen atom to form an asymmetric centre (carbon atom), which phosphinitemethyl group serves at the same time as a chelating group. Those substituted oxazolines form with TM8 metals chiral complexes that are excellent catalysts for the enantioselective addition of hydrogen, borohydrides or silanes to a carbon-carbon or carbon-hetero atom multiple bond in prochiral organic compounds or of C-nucleophiles or amines to allylic compounds or for the enantioselective coupling of aryl or alkenyl triflates to olefins (Heck reaction). Especially in the enantio-selective hydrogenation of prochiral olefins catalysed with Ir complexes, particularly high optical yields are observed. In addition, the phosphinite groups in the ligands exhibit a surprisingly high stability towards hydrolysis. The starting materials for the preparation of the ligands are simple, in some cases commercially available organic molecules that can be combined with one another in a variety of ways, so that the steric and electronic properties of the ligands in respect of catalytic activity and steric selectivity can be adapted to the substrates to be reacted in an outstanding manner.
The invention relates to compounds of formulae I and Ia, 
wherein
X1 is secondary phosphino;
R3 is hydrogen, a hydrocarbon radical having from 1 to 20 carbon atoms, a heterohydro-carbon radical, bonded via a carbon atom, having from 2 to 20 atoms and at least one hetero atom selected from the group OS and NR, or ferrocenyl;
R is H or C1-C4alkyl;
each R4 individually or both R4 together are a hydrocarbon radical having from 1 to 20 carbon atoms; and
R01 and R02 are each independently of the other a hydrogen atom or a hydrocarbon radical having from 1 to 20 carbon atoms.
The phosphine group X1 may contain two identical or two different hydrocarbon radicals or the two hydrocarbon radicals may form with the P atom a 3- to 8-membered ring. Preferably the phosphine group contains two identical hydrocarbon radicals. The hydrocarbon radicals may be unsubstituted or substituted and they may contain from 1 to 22, preferably from 1 to 12, carbon atoms. Of the compounds of formulae I and la special preference is given to those wherein the phosphine group contains two identical or different radicals selected from the group: linear or branched C1-C12alkyl; C5-C12cycloalkyl or C5-C12cycloalkyl-CH2xe2x80x94 unsubstituted or substituted by C1-C6alkyl or by C1-C6alkoxy; phenyl or benzyl; and phenyl or benzyl substituted by halogen (for example F, Cl and Br), C1-C6alkyl, C1-C6haloalkyl (for example trifluoromethyl), C1-C6alkoxy, C1-C6haloalkoxy (for example trifluoromethoxy), (C6H5)3Si, (C1-C12alkyl)3Si, secondary amino or by xe2x80x94CO2xe2x80x94C1-C6alkyl (for example xe2x80x94CO2CH3).
The two radicals in the phosphine group may together also be dimethylene, trimethylene, tetramethylene or pentamethylene unsubstituted or substituted by halogen, C1-C6alkyl or by C1-C6alkoxy. The substituents are preferably bonded in the two ortho positions to the P atom.
The phosphine groups may also be those of formulae 
wherein o and p are each independently of the other an integer from 2 to 10, and the sum of o+p is from 4 to 12, preferably from 5 to 8, and the phenyl rings are unsubstituted or substituted by C1-C4alkyl and C1-C4alkoxy. Examples are [3.3.1]- and [4.2.1]-phobyl of the formulae 
Examples of secondary phosphine groups in which the two hydrocarbon radicals form with the P atom a 3- to 8-membered ring are especially those of the formula 
which may be substituted in one or both ortho positions and optionally the meta positions to the P atom by C1-C4alkyl and/or by C1-C4alkoxy.
Examples of P substituents as alkyl, which preferably contains from 1 to 6 carbon atoms, are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and the isomers of pentyl and hexyl. Examples of P substituents as unsubstituted or alkyl-substituted cycloalkyl are cyclopentyl, cyclohexyl, methyl- and ethyl-cyclohexyl and dimethylcyclohexyl. Examples of P substituents as phenyl and benzyl substituted by alkyl, alkoxy, haloalkyl and/or by haloalkoxy are methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, methylbenzyl, methoxyphenyl, dimethoxyphenyl, trifluoromethylphenyl, bis-trifluoromethylphenyl, tris-trifluoromethylphenyl, trifluoromethoxyphenyl and bis-trifluoromethoxyphenyl.
Preferred phosphine groups X1 are those which contain identical or different, preferably identical, radicals selected from the group C1-C6alkyl; cyclopentyl or cyclohexyl unsubstituted or substituted by from 1 to 3 C1-C4alkyl or C1-C4alkoxy substituents; benzyl and especially phenyl, which are unsubstituted or substituted by from 1 to 3 C1-C4alkyl, C1-C4alkoxy, F, Cl, C1-C4fluoroalkyl or C1-C4fluoroalkoxy substituents.
In the compounds of formula I, X1 is preferably the group xe2x80x94PR1R2 wherein R1 and R2 are each independently of the other a hydrocarbon radical having from 1 to 20 carbon atoms, which is unsubstituted or substituted by halogen, C1-C6alkyl, C1-C6haloalkyl, C1-C6alkoxy, C1-C6haloalkoxy, (C6H5)3Si, (C1-C12alkyl)3Si or by xe2x80x94CO2xe2x80x94C1-C6alkyl; or wherein R1 and R2 together are dimethylene, trimethylene, tetramethylene or pentamethylene unsubstituted or substituted by C1-C4alkyl and/or by C1-C4alkoxy.
R1 and R2 are preferably identical or different, especially identical, radicals selected from the group: branched C3-C6alkyl; cyclopentyl or cyclohexyl unsubstituted or substituted by from one to three C1-C4alkyl or C1-C4alkoxy substituents; benzyl unsubstituted or substituted by from one to three C1-C4alkyl or C1-C4alkoxy substituents, and especially phenyl unsubstituted or substituted by from one to three C1-C4alkyl, C1-C4alkoxy, xe2x80x94NH2, OH, F, Cl, C1-C4fluoroalkyl or C1-C4fluoroalkoxy substituents.
R1 and R2 are more especially identical or different, especially identical, radicals selected from the group: phenyl unsubstituted or substituted by from one to three C1-C4alkyl, C1-C4alkoxy or C1-C4fluoroalkyl substituents.
The radicals R3 and R4 may be unsubstituted or substituted, for example by C1-C6alkyl, C1-C6alkoxy, cyclohexyl, C6-C10aryl, C7-C12aralkyl, C1-C4alkyl-C6-C10aryl, C1C4alkoxy-C6-C10aryl, C1-C4alkyl-C7-C12aralkyl, C1-C4alkoxy-C7-C12aralkyl, xe2x80x94COxe2x80x94OR5, xe2x80x94COxe2x80x94NR6R7 or by xe2x80x94NR6R7, wherein R5 is H, an alkali metal, C1-C6alkyl, cyclohexyl, phenyl or benzyl, and R6 and R7 are each independently of the other hydrogen, C1-C6alkyl, cyclohexyl, phenyl or benzyl, or R6 and R7 together are tetramethylene, pentamethylene or 3-oxapentylene.
The hydrocarbon radical R3 contains preferably from 1 to 16, more especially from 1 to 12, carbon atoms. The hydrocarbon radical R3 may be C1-C18alkyl, preferably C1-C12alkyl and more especially C1-C8alkyl; C3-C12cycloalkyl, preferably C4-C8cycloalkyl and more especially C5-C6cycloalkyl; or C6C16aryl and preferably C6-C12aryl.
When R3 is alkyl, it is preferably branched C3-C8alkyl. Examples of alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and eicosyl. Preferred alkyl is isopropyl, isobutyl, tert-butyl, isopentyl, isohexyl and 1,1,2,2-tetramethylethyl.
When R3 is cycloalkyl, it may be, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl or cyclododecyl.
When R3 is aryl, it may be, for example, phenyl, naphthyl, anthracenyl, phenanthryl, biphenyl or ferrocenyl.
The heterohydrocarbon radical R3 contains preferably a total of from 1 to 16, more especially a total of from 1 to 12, atoms and from 1 to 3 hetero atoms selected from the group O, S and NR. The heterohydrocarbon radical R3 may be C1-C18heteroalkyl, preferably C1-C2heteroalkyl and more especially C1-C8heteroalkyl; C3-C12heterocycloalkyl, preferably C4-C8heterocycloalkyl and more especially C4-C5heterocycloalkyl; or C4-C16heteroaryl and preferably C4-C11heteroaryl.
When R3 is ferrocenyl, the ferrocenyl is unsubstituted or substituted by at least one C1-C4alkyl, C1-C4alkoxy, trimethylsilyl or halogen substituent, for example methyl, ethyl, n- or iso-propyl, butyl, methoxy, ethoxy, F, Cl or Br.
When R3 is alkyl, it is preferably C1-C8alkyl. Examples of heteroalkyl are methoxymethyl, methoxyethyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, isopropoxymethyl, isopropoxyethyl, isobutoxyethyl, tert-butoxyethyl, methylthioethyl and dimethylaminoethyl.
When R3 is heterocycloalkyl, it may be, for example, oxetanyl, tetrahydrofuranyl, oxacyclohexyl, dioxanyl, pyrrolidinyl or N-methylazacyclohexyl.
When R3 is heteroaryl, it may be, for example, furanyl, thiophenyl, pyrrolyl, pyridinyl, pyrimidinyl, indolyl, quinolinyl or quinoxalinyl.
In a preferred sub-group, R3 is a hydrocarbon radical selected from the group: branched C3-C12alkyl, C5-C6cycloalkyl, ferrocenyl and C6-C12aryl, the cyclic radicals being unsubstituted or substituted by halogen (F, Cl, Br), C1-C4alkyl or by C1-C4alkoxy.
R4 as a hydrocarbon radical contains preferably from 1 to 16, especially from 1 to 12, more especially from 1 to 8, carbon atoms. The hydrocarbon radical R4 may be C1-C18alkyl, preferably C1-C12alkyl and more especially C1-C8alkyl; C3-C12cycloalkyl, preferably C4-C8cycloalkyl and more especially C5-C6cycloalkyl; C6-C16aryl and preferably C6-C12aryl, or C7-C16aralkyl and preferably C7-C12aralkyl.
When the two R4 are a hydrocarbon radical, that radical is alkylene, which preferably contains from 3 to 7, more especially from 4 to 6, carbon atoms. Examples are 1,3-propylene, 1,3- or 1,4-butylene, 1,3-, 1,4- or 1,5-pentylene and 1,3-, 1,4-, 1,5-, 2,5-, 2,6- or 1,4-hexylene.
The embodiments and preferences given for R3 apply to R4 in respect of alkyl, cycloalkyl and aryl. When R4 is aralkyl, it is preferably benzyl or naphthylmethyl, which are unsubstituted or substituted by halogen (F, Cl, Br), C1-C4alkyl or by C1-C4alkoxy.
In a preferred sub-group, R4 is a hydrocarbon radical selected from the group: branched C3-C12alkyl, C5-C6cycloalkyl, C6-C12aryl and C7-C12aralkyl, the cyclic radicals being unsubstituted or substituted by halogen (F, Cl, Br), C1-C4alkyl, C1-C4haloalkyl (for example trifluoromethyl) or by C1-C4alkoxy.
The embodiments and preferences given for R4 apply independently to R01 and R02. When R01 and R02 are different radicals or one of R01 and R02 is a hydrogen atom, the compounds of formulae I and Ia contain a further chiral carbon atom. The invention relates also to racemates or diastereoisomers of those compounds. The relative configuration of the diastereoisomers may have a positive influence on the enantioselectivity in addition reactions catalysed according to the invention. R01 and R02 are preferably each hydrogen. In another preferred group, R01 is hydrogen and R02 is C1-C4alkyl.
A preferred sub-group of the compounds according to the invention comprises those of formulae Ib and Ic, 
wherein
X1 is xe2x80x94PR1R2,
R1 and R2 are identical or different, especially identical, radicals selected from the group: xcex1-branched C3-C6alkyl; C5-C7cycloalkyl unsubstituted or substituted by from one to three C1-C4alkyl or C1-C4alkoxy substituents; phenyl unsubstituted or substituted by from one to three C1-C4alkyl, C1-C4alkoxy or C1-C4fluoroalkyl substituents; and dimethylene, trimethylene, tetramethylene or hexamethylene unsubstituted or substituted by C1-C4alkyl or by C1-C4alkoxy;
R3 is a hydrocarbon radical selected from the group: branched C3-C12alkyl, C5-C6cycloalkyl, C6-C12aryl and ferrocenyl, the cyclic radicals being unsubstituted or substituted by halogen, C1-C4alkyl, C1-C4haloalkyl or by C1-C4alkoxy; and
R4 is a hydrocarbon radical selected from the group: branched C3-C12alkyl, C5-C6cycloalkyl, C6-C12aryl and C7C12aralkyl, the cyclic radicals being unsubstituted or substituted by halogen, C1-C4alkyl or by C1-C4alkoxy.
The compounds of formulae I and Ia can be prepared in a small number of process steps in two different ways, xcex1-amino-xcex2-hydroxycarboxylic acid esters being a fundamental reagent. In a first variant, iminocarboxylic acid esters are cyclised with xcex1-amino-xcex2-hydroxycarboxylic acid esters to form oxazolinecarboxylic acid esters, the ester group is then converted into a tertiary alcohol group, and subsequently the phosphonite is formed. In a second variant, a carboxylic acid or a carboxylic acid derivative is reacted with an xcex1-amino-xcex2-hydroxycarboxylic acid ester, the ester group is then converted into a tertiary alcohol group, cyclisation to the oxazoline is carried out and subsequently the phosphonite is formed.
The invention relates also to a process for the preparation of compounds of formulae I and Ia, 
wherein R01, R02, R3, R4 and X1 are as defined above, and xcx9c denotes the R- or S-form, in which process either
a1) a compound of formula II 
or a salt thereof, wherein R3 is as defined above and R8 is C1-C4alkyl, is reacted with at least an equivalent amount of a compound of formula III, 
wherein R9 is C1-C4alkyl, to form a compound of formula IV, 
a2) the compound of formula IV is reacted with at least 2 equivalents of an organometal compound of formula V or Va
R4xe2x80x94X2xe2x80x83xe2x80x83(V),
R4xe2x80x94(X2)2xe2x80x83xe2x80x83(Va),
wherein R4 is as defined above, X2 is an alkali metal or xe2x80x94Me1X3, Me1 is Mg or Zn, and X3 is Cl, Br or I, to form a compound of formula VI 
and
a3) the hydroxyl group in the compound of formula VI is metallated and then reacted with a halophosphine of formula VII,
X1xe2x80x94Y1xe2x80x83xe2x80x83(VII),
wherein X1 is as defined above and Y1 is Cl, Br or I, to form a compound of formula Ia or Ib; or
b1) a carboxylic acid of formula VIII
R3xe2x80x94COOHxe2x80x83xe2x80x83(VIII),
or a derivative of that carboxylic acid, is reacted with a compound of formula III to form a carboxylic acid amide of formula IX, 
b2) the compound of formula IX is reacted with a compound of formula V or Va to form a compound of formula X, 
b3) the compound of formula X is cyclised to form a compound of formula VI; and
b4) the hydroxyl group in the compound of formula VI is metallated and then reacted with a halophosphine of formula VII to form a compound of formula Ia or Ib.
The invention relates also to compounds of formula IV wherein R01 is a hydrogen atom and R02 is a hydrocarbon radical having from 1 to 20 carbon atoms, and R3, R4 and R9 are as defined above.
The invention relates also to compounds of formula VI wherein R01 and R02 are each independently of the other a hydrogen atom or a hydrocarbon radical having from 1 to 20 carbon atoms, and R3 and R4 are as defined above.
Process Step a1)
The preparation of iminocarboxylic acid esters of formula II is generally known and is described, for example, by L. Weintraub et al. in J. Org. Chem., Volume 33, No. 4, pages 1679 to 1681 (1968). The iminocarboxylic acid esters of formula II are advantageously used in the form of salts, for example tetrafluoroborates. In formula II, R8 may be, for example, methyl, ethyl, n- or iso-propyl or butyl. The reaction can be carried out at temperatures of from 20 to 150xc2x0 C. It is advantageous to use solvents such as, for example, halogenated hydrocarbons (methylene chloride, trichloromethane or tetrachloroethane). Equivalent amounts of the reactants are generally used. Serinecarboxylic acid esters of formula III are known. R9 may be, for example, methyl, ethyl, n- or iso-propyl or butyl.
Process Step a2)
The reaction of carboxylic acid esters with metal or metal halide hydrocarbons is known per se. When X2 is an alkali metal, it may be Na, K or especially Li. In the group Me1X3, Me1 may be, for example, Mg or Zn. The reaction is advantageously carried out by adding the compound of formula V at low temperatures, for example from xe2x88x9230 to xe2x88x9280xc2x0 C., to a solution of the compound of formula IV and then heating the mixture, for example to room temperature. The reaction can then be completed at that temperature or at higher temperatures (up to the boiling temperature of the solvents used). Suitable solvents are especially ethers, such as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane.
Process Step a3)
The metallation of the compound of formula VI to form metal alcoholates can be carried out with alkali metal alkyls and especially lithium alkyl, for example lithium methyl, ethyl, propyl or butyl, or with Grignard reagents, such as methyl-, ethyl-, propyl-, butyl- or benzyl-magnesium halides. It is advantageous to use equivalent amounts or a slight excess of alkali metal alkyls or Grignard reagents. The addition is advantageously made at relatively low temperatures, for example from xe2x88x9220 to xe2x88x9280xc2x0 C. The presence of tertiary amines, for example trimethyl-, triethyl- or tributyl-amine or tetramethylethylenediamine may be advantageous. Then at room temperature the reaction can be completed, the halophosphine of formula VII added and the reaction ended at that temperature. The reaction is preferably carried out in the presence of inert solvents, for example ethers or hydrocarbons (pentane, hexane, cyclohexane, methylcyclohexane, benzene, toluene or xylene).
Process Step b1)
Suitable derivatives of carboxylic acids are esters, amides and especially halides. The reaction is advantageously carried out in the presence of solvents, for example halogenated hydrocarbons. When carboxylic acids of formula VII are used, the addition of equimolar amounts of tertiary amines is advantageous, for example diisopropylethylamine. The presence of at least equimolar amounts of carbodiimides is also advantageous. In order to suppress racemisation, the carboxylic acids can be converted into activated esters in the presence of metal salts, for example copper salts, with selected alcohols, for example hydroxybenzotriazole. The reaction can be carried out at temperatures of from xe2x88x9230 to 50xc2x0 C.
Process Step b2)
This reaction can be carried out analogously to Process step a2).
Process Step b3)
The reaction is advantageously carried out in the presence of a solvent, for example halogenated hydrocarbons, and at temperatures of preferably from 50 to 150xc2x0 C. A tertiary amine, for example triethylamine, and a sulfonic acid halide, such as p-toluenesulfonyl chloride, are added to a solution of the compound of formula X and the mixture is heated to reflux temperature. The reaction mixture is left to react for a period of time, water is added and then the reaction mixture is allowed to react to completion.
Process Step b4)
This reaction can be carried out analogously to Process step a3).
The compounds of formulae Ia and Ib are obtained in good total yields. By selection of the starting compounds it is possible for the compounds according to the invention to be synthesised in a modular manner, the simple starting compounds allowing a large number of substitutions in respect of R3 and R4.
The invention relates also to the intermediates of formulae IV, VI and X obtainable in the process according to the invention.
The compounds of formulae Ia and Ib according to the invention are ligands for metal complexes selected from the group of TM8 metals, especially from the group Ru, Rh and Ir, which are excellent catalysts or catalyst precursors for asymmetric syntheses, for example the asymmetric hydrogenation of prochiral, unsaturated, organic compounds. When prochiral unsaturated organic compounds are used, it is possible to induce a very large excess of optical isomers in the synthesis of organic compounds and to achieve a high chemical conversion in short reaction times. The enantioselectivities and catalyst activities that are achievable are excellent.
The invention relates also to metal complexes of metals selected from the group of TM8 metals with compounds of formulae I and Ia as ligands.
Examples of metals that come into consideration are Cu, Ag, Au, Ni, Co, Rh, Pd, Ir and Pt. Preferred metals are rhodium and iridium and also ruthenium, platinum and palladium.
Especially preferred metals are ruthenium, rhodium and iridium.
The metal complexes may, according to the oxidation state and coordination number of the metal atom, contain further ligands and/or anions. They may also be cationic metal complexes. Such analogous metal complexes and their preparation are frequently described in the literature.
The metal complexes may correspond, for example, to the general formulae XI and XII,
A1MeLnxe2x80x83xe2x80x83(XI),
(A1MeLn)(z+)(Exe2x88x92)zxe2x80x83xe2x80x83(XII),
wherein
A1 is a compound of formula I or Ia,
L denotes identical or different, monodentate, anionic or non-ionic ligands, or two L denote identical or different, bidentate, anionic or non-ionic ligands;
n is 2, 3 or 4 when L is a monodentate ligand, or n is 1 or 2 when L is a bidentate ligand;
z is 1, 2 or 3;
Me is a metal selected from the group Rh, Ir and Ru; the metal having the oxidation state 0, 1, 2, 3 or 4;
Exe2x88x92 is the anion of an oxyacid or complex acid; and the anionic ligands balance the charge of oxidation states 1, 2, 3 or 4 of the metal.
The preferences and embodiments described above apply to the compounds of formulae I and Ia.
Monodentate non-ionic ligands may be selected, for example, from the group of olefins (for example ethylene, propylene), allyls (allyl, 2-methallyl), solvating solvents (nitriles, linear or cyclic ethers, optionally N-alkylated amides and lactams, amines, phosphines, alcohols, carboxylic acid esters, sulfonic acid esters), nitrogen monoxide and carbon monoxide.
Monodentate anionic ligands may be selected, for example, from the group halide: (F, Cl, Br, I), pseudohalide (cyanide, cyanate, isocyanate) and anions of carboxylic acids, sulfonic acids and phosphonic acids (carbonate, formate, acetate, propionate, methylsulfonate, trifluoromethylsulfonate, phenylsulfonate, tosylate).
Bidentate non-ionic ligands may be selected, for example, from the group of linear or cyclic diolefins (for example hexadiene, cyclooctadiene, norbornadiene), dinitriles (malonic dinitrile), optionally N-alkylated carboxylic acid diamides, diamines, diphosphines, diols, acetonyl acetonates, dicarboxylic acid diesters and disulfonic acid diesters.
Bidentate anionic ligands may be selected, for example, from the group of anions of dicarboxylic acids, disulfonic acids and diphosphonic acids (for example of oxalic acid, malonic acid, succinic acid, maleic acid, methylenedisulfonic acid and methylenediphosphonic acid).
Preferred metal complexes are also those wherein E is xe2x80x94Clxe2x88x92, xe2x80x94Brxe2x88x92, xe2x80x94Ixe2x88x92, ClO4xe2x88x92, CF3SO3xe2x88x92, CH3SO3xe2x88x92, HSO4xe2x88x92, (CF3SO2)2Nxe2x88x92, (CF3SO2)3Cxe2x88x92, tetraaryl borates, for example B(phenyl)4xe2x88x92, B[bis(3,5-trifluoromethyl)phenyl]4xe2x88x92, B[bis(3,5-dimethyl)phenyl]4xe2x88x92, B(C6F5)4xe2x88x92 and B(4-methylphenyl)4xe2x88x92, BF4xe2x88x92, PF6xe2x88x92, SbCl6xe2x88x92, AsF6xe2x88x92 or SbF6xe2x88x92.
Especially preferred metal complexes, which are particularly suitable for hydrogenations, correspond to formulae XIII and XIV,
[A1Me2YZ]xe2x80x83xe2x80x83(XIII),
[A1Me2Y]+E1xe2x88x92xe2x80x83xe2x80x83(XIV),
wherein
A1 is a compound of formula I or Ia;
Me2 is rhodium or iridium;
Y denotes two olefins or a diene;
Z is Cl, Br or I; and
E1xe2x88x92 is the anion of an oxyacid or complex acid.
The embodiments and preferences described above apply to the compounds of formulae I and Ia.
Y as olefin may denote C2-C12-, preferably C2-C6- and more especially C2-C4-olefin. Examples are propene, but-1-ene and especially ethylene. The diene may contain from 5 to 12, preferably from 5 to 8, carbon atoms and it may be an open-chain, cyclic or polycyclic diene. The two olefin groups of the diene are preferably bonded by one or two CH2 groups. Examples are 1,3-pentadiene, cyclopentadiene, 1,5-hexadiene, 1,4-cyclohexadiene, 1,4- or 1,5-heptadiene, 1,4- or 1,5-cycloheptadiene, 1,4- or 1,5-octadiene, 1,4- or 1,5-cyclooctadiene and norbornadiene. Y preferably denotes two ethylene or 1,5-hexadiene, 1,5-cyclooctadiene or norbornadiene.
In formula XIII, Z is preferably Cl or Br. Examples of E1 are BF4xe2x88x92, ClO4xe2x88x92, CF3SO3xe2x88x92, CH3SO3xe2x88x92, HSO4xe2x88x92, B(phenyl)4xe2x88x92, B[bis(3,5-trifluoromethyl)phenyl]4xe2x88x92, PF6xe2x88x92, SbCl6xe2x88x92, AsF6xe2x88x92 and SbF6xe2x88x92.
The metal complexes according to the invention are prepared in accordance with methods known in the literature (see also U.S. Pat. Nos. 5,371,256, 5,446,844, 5,583,241, and E. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Comprehensive Asymmetric Catalysis I to III, Springer Verlag, Berlin, 1999, and literature referred to therein).
The metal complexes according to the invention are homogeneous catalysts, or catalyst precursors capable of being activated under the reaction conditions, which can be used for asymmetric addition reactions with prochiral, unsaturated, organic compounds.
The metal complexes can be used, for example, for the asymmetric hydrogenation (addition of hydrogen) of prochiral compounds having carbon-carbon or carbon-hetero atom multiple bonds, especially double bonds. Such hydrogenations with soluble homogeneous metal complexes are described, for example, in Pure and Appl. Chem., Vol. 68, No. 1, pp. 131-138 (1996). Preferred unsaturated compounds to be hydrogenated contain the groups Cxe2x95x90C, Cxe2x95x90N and/or Cxe2x95x90O. For the hydrogenation the use of metal complexes of rhodium and iridium is preferred according to the invention.
The metal complexes according to the invention can also be used as catalysts in the asymmetric hydroboration (addition of borohydrides) of prochiral organic compounds having carbon-carbon double bonds. Such hydroborations are described, for example, by Tamio Hayashi in E. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Comprehensive Asymmetric Catalysis I to III, Springer Verlag, Berlin, 1999, pages 351 to 364. Suitable borohydrides are, for example, catechol boranes. The chiral boron compounds can be used in syntheses and/or reacted in a manner known per se to form other chiral organic compounds that are valuable building blocks for the preparation of chiral intermediates or active ingredients. One example of such a reaction is the preparation of 3-hydroxy-tetrahydrofuran (according to DE 198 07 330).
The metal complexes according to the invention can also be used as catalysts in the asymmetric hydrosilylation (addition of silanes) of prochiral organic compounds having carbon-carbon or carbon-hetero atom double bonds. Such hydrosilylations are described, for example, by G. Pioda and A. Togni in Tetrahedron: Asymmetry, 1998, 9, 3093 or by S. Uemura, et al. in Chem. Commun. 1996, 847. Suitable silanes are, for example, trichlorosilane or diphenylsilane. For the hydrosilylation of, for example, Cxe2x95x90O and Cxe2x95x90N groups it is preferable to use metal complexes of rhodium and iridium. For the hydrosilylation of, for example, Cxe2x95x90C groups it is preferable to use metal complexes of palladium. The chiral silyl compounds can be used in syntheses and/or reacted in a manner known per se to form other chiral organic compounds that are valuable building blocks for the preparation of chiral intermediates or active ingredients. Examples of such reactions are hydrolysis to alcohols.
The metal complexes according to the invention can also be used as catalysts for asymmetric allylic substitution reactions (addition of C-nucleophiles to allyl compounds). Such allylations are described, for example, by A. Pfaltz and M. Lautens in E. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Comprehensive Asymmetric Catalysis I to III, Springer Verlag, Berlin, 1999, pages 833 to 884. Suitable precursors for allyl compounds are, for example, 1,3-diphenyl-3-acetoxy-1-propene and 3-acetoxy-1-cyclohexene. For that reaction it is preferable to use metal complexes of palladium. The chiral allyl compounds can be used in syntheses for the preparation of chiral intermediates or active ingredients.
The metal complexes according to the invention can also be used as catalysts in asymmetric amination (addition of amines to allyl compounds) or in asymmetric Heck reactions. Such aminations are described, for example, by A. Pfaltz and M. Lautens in E. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Comprehensive Asymmetric Catalysis I to III, Springer Verlag, Berlin, 1999, pages 833 to 884, and Heck reactions by O. Loiseleur et al. in Journal of Organometallic Chemistry 576 (1999), pages 16 to 22. Suitable amines, in addition to ammonia, are primary and secondary amines. For the amination of allyl compounds it is preferable to use metal complexes of palladium. The chiral amines can be used in syntheses for the preparation of chiral intermediates or active ingredients.
The invention relates also to the use of the metal complexes according to the invention as homogeneous catalysts in the preparation of chiral organic compounds by asymmetric addition of hydrogen, borohydrides or silanes to a carbon-carbon or carbon-hetero atom multiple bond in prochiral organic compounds or asymmetric addition of C-nucleophiles or amines to allyl compounds.
The invention relates further to a process for the preparation of chiral organic compounds by asymmetric addition of hydrogen, borohydrides or silanes to a carbon-carbon or carbon-hetero atom multiple bond in prochiral organic compounds or asymmetric addition of C-nucleophiles or amines to allyl compounds in the presence of a catalyst, wherein the addition is carried out in the presence of catalytic amounts of at least one metal complex according to the invention.
Preferred prochiral unsaturated compounds to be hydrogenated may contain one or more, identical or different groups Cxe2x95x90C, Cxe2x95x90N and/or Cxe2x95x90O in open-chain or cyclic organic compounds, the groups Cxe2x95x90C, Cxe2x95x90N and/or Cxe2x95x90O being part of a ring system or being exocyclic groups. The prochiral unsaturated compounds may be alkenes, cycloalkenes and heterocycloalkenes, and also open-chain or cyclic ketones, ketimines and ketohydrazones. They may correspond, for example, to formula X,
R07R08Cxe2x95x90Dxe2x80x83xe2x80x83(XVIII),
wherein
R07 and R08 are so selected that the compound is prochiral and are each independently of the other an open-chain or cyclic hydrocarbon radical or heterohydrocarbon radical having hetero atoms selected from the group O, S and N, that contains from 1 to 30, preferably from 1 to 20, carbon atoms;
D is O or a radical of formula Cxe2x95x90R09R10 or NR11;
R09 and R10 each independently of the other have the same meanings as R07 and R08,
R11 is hydrogen, C1-C12alkyl, C1-C12alkoxy, C3-C12cycloalkyl, C3-C12cycloalkyl-C1-C6alkyl, C3-C11heterocycloalkyl, C3-C11heterocycloalkyl-C1-C6alkyl, C6-C14aryl, C5-C13heteroaryl, C7-C16aralkyl or C6-C14heteroaralkyl,
R07 and R08 together with the carbon atom to which they are bonded form a hydrocarbon ring or heterohydrocarbon ring having from 3 to 12 ring members;
R07 and R08 each together with the Cxe2x95x90C group to which they are bonded form a hydrocarbon ring or heterohydrocarbon ring having from 3 to 12 ring members;
R07 and R11, each together with the Cxe2x95x90N group to which they are bonded form a hydrocarbon ring or heterohydrocarbon ring having from 3 to 12 ring members;
the hetero atoms in the heterocyclic rings being selected from the group O, S and N; and R07, R08, R09, R10 and R11 are unsubstituted or substituted by C1-C6alkyl, C1-C6alkoxy, cyclohexyl, C6-C10aryl, C7-C12aralkyl, C1-C4alkyl-C6-C10aryl, C1-C4alkoxy-C6-C10aryl, C1-C4alkyl-C7-C12aralkyl, C1-C4alkoxy-C7-C12aralkyl, xe2x80x94OH, xe2x95x90O, xe2x80x94COxe2x80x94OR12, xe2x80x94COxe2x80x94NR13R14 or by xe2x80x94NR13R14, wherein R12 is H, an alkali metal, C1-C6alkyl, cyclohexyl, phenyl or benzyl, and R13 and R14 are each independently of the other hydrogen, C1-C6alkyl, cyclohexyl, phenyl or benzyl, or R13 and R14 together are tetramethylene, pentamethylene or 3-oxapentylene.
Examples and preferences for substituents have been given above.
R07 and R08 may be, for example, C1-C20alkyl and preferably C1-C12alkyl, C1-C20heteroalkyl and preferably C1-C12heteroalkyl having hetero atoms selected from the group O, S and N, C3-C12cycloalkyl and preferably C4-C8cycloalkyl, C-bonded C3-C11heterocycloalkyl and preferably C4-C8heterocycloalkyl having hetero atoms selected from the group O, S and N, C3-C12cycloalkyl-C1-C6alkyl and preferably C4-C8cycloalkyl-C1-C6alkyl, C3-C11heterocycloalkyl-C1-C6alkyl and preferably C4-C8heterocycloalkyl-C1-C6alkyl having hetero atoms selected from the group O, S and N, C6-C14aryl and preferably C6-C10aryl, C5-C13heteroaryl and preferably C5-C9heteroaryl having hetero atoms selected from the group O, S and N, C7-C15aralkyl and preferably C7-C11aralkyl, C6-C12heteroaralkyl and preferably C6-C10heteroaralkyl having hetero atoms selected from the group O, S and N.
When R07 and R08, R07 and R09, or R07 and R11, in each case together with the group to which they are bonded, form a hydrocarbon ring or heterohydrocarbon ring, that ring preferably contains from 4 to 8 ring members. The heterohydrocarbon ring may contain, for example, from 1 to 3, preferably one or two, hetero atoms.
R11 is preferably hydrogen, C1-C6alkyl, C1-C6alkoxy, C4-C8cycloalkyl, C4-C8cycloalkyl-C1-C4alkyl, C4-C10heterocycloalkyl, C4-C10heterocycloalkyl-C1-C4alkyl, C6-C10aryl, C5-C9heteroaryl, C7-C12aralkyl or C5-C13heteroaralkyl.
Some examples of unsaturated organic compounds are acetophenone, 4-methoxyacetophenone, 4-trifluoromethylacetophenone, 4-nitroacetophenone, 2-chloroacetophenone, corresponding unsubstituted or N-substituted acetophenonebenzylimines, unsubstituted or substituted benzocyclohexanone or benzocyclopentanone and corresponding imines, imines from the group of unsubstituted or substituted tetrahydroquinoline, tetrahydropyridine and dihydropyrrole, and unsaturated carboxylic acids, esters, amides and salts, for example xcex1- and optionally xcex2-substituted acrylic acids or crotonic acids. Preferred carboxylic acids are those of the formula
R12xe2x80x94CHxe2x95x90C(R13)xe2x80x94C(O)OH
and their salts, esters and amides, wherein R12 is C1-C6alkyl; C3-C8cycloalkyl unsubstituted or substituted by from 1 to 4 C1-C6alkyl, C1-C6alkoxy or C1-C6alkoxy-C1-C4alkoxy substituents, or C6-C10aryl, preferably phenyl, unsubstituted or substituted by from 1 to 4 C1-C6alkyl, C1-C6alkoxy or C1-C6alkoxy-C1-C4alkoxy substituents; and R13 is linear or branched C1-C4C1-C6alkyl (for example isopropyl) or, unsubstituted or substituted as defined above, cyclopentyl, cyclohexyl, phenyl or protected amino (for example acetylamino).
The process according to the invention can be carried out at low or elevated temperatures, for example from xe2x88x9220 to 150xc2x0 C., preferably from xe2x88x9210 to 100xc2x0 C., more especially from 10 to 80xc2x0 C. The optical yields are generally better at lower temperature than at higher temperatures.
The process according to the invention can be carried out at normal pressure or excess pressure. The pressure may be, for example, from 105 to 2xc3x97107 Pa (Pascal). Hydrogenations can be carried out at normal pressure or at excess pressure. Better selectivities are often observed at normal pressure.
Catalysts are used preferably in amounts of from 0.0001 to 10 mol %, especially from 0.001 to 10 mol %, more especially from 0.01 to 5 mol %, based on the compound to be hydrogenated.
The preparation of the ligands and catalysts and also the addition reaction can be carried out without a solvent or in the presence of an inert solvent, it being possible to use one solvent or a mixture of solvents. Examples of suitable solvents are aliphatic, cycloaliphatic and aromatic hydrocarbons (pentane, hexane, petroleum ether, cyclohexane, methylcyclohexane, benzene, toluene, xylene), aliphatic halogenated hydrocarbons (methylene chloride, chloroform, di- and tetra-chloroethane), nitrites (acetonitrile, propionitrile, benzonitrile), ethers (diethyl ether, dibutyl ether, tert-butyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, diethylene glycol monomethyl or monoethyl ether), ketones (acetone, methyl isobutyl ketone), carboxylic acid esters and lactones (ethyl or methyl acetate, valerolactone), N-substituted lactams (N-methylpyrrolidone), carboxylic acid amides (dimethylamide, dimethylformamide), acyclic ureas (dimethylimidazoline), and sulfoxides and sulfones (dimethyl sulfoxide, dimethyl sulfone, tetramethylene sulfoxide, tetramethylene sulfone) and alcohols (methanol, ethanol, propanol, butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether) and water. The solvents can be used on their own or in a mixture of at least two solvents.
The reaction can be carried out in the presence of co-catalysts, for example quaternary ammonium halides (tetrabutylammonium iodide) and/or in the presence of protonic acids, for example mineral acids (see, for example, U.S. Pat. Nos. 5,371,256, 5,446,844 and 5,583,241 and EP-A-0 691 949). The co-catalysts are especially suitable for hydrogenations.
The metal complexes used as catalysts can be added in the form of separately prepared isolated compounds or alternatively they can be formed in situ prior to the reaction and then mixed with the substrate to be hydrogenated. It may be advantageous, when isolated metal complexes are being used in the reaction, additionally to add ligands or, in the case of in situ preparation, to use the ligands in excess. The excess may be, for example, from 1 to 10 mol, preferably from 1 to 5 mol, based on the metal compound used for preparation.
The process according to the invention is generally carried out by first introducing the catalyst into the reaction vessel and then adding the substrate, optionally reaction auxiliaries and the addition reaction compound and subsequently starting the reaction. Compounds to be added that are in gaseous form, for example hydrogen or ammonia, are preferably introduced under pressure. The process can be carried out continously or intermittently in various types of reactor.
The chiral organic compounds that can be prepared according to the invention are active ingredients or intermediates in the preparation of such ingredients, especially in the field of the manufacture of pharmaceuticals and agrochemicals. For example, o,o-dialkyl aryl-ketamine derivatives, especially those having alkyl and/or alkoxyalkyl groups, are effective as fungicides, especially as herbicides. The derivatives may be amine salts, acid amides, for example of choroacetic acid, tertiary amines and ammonium salts (see e.g. EP-A-0 077 755 and EP-A-0 115 470).
The following Examples illustrate the invention. Chromatographic separation and purification is carried out using C-Gel C-560 (Uetikon AG, Switzerland).